Effects of Photoperiod on the Cessation of Growth during Autumn in Male Red Deer and Growth Hormone and Insulin-like Growth Factor-I Secretion

Webster, James R.; Corson, I. D.; Littlejohn, R. P.; Stuart, S. K.; Suttie, J. M.

doi:10.1006/gcen.1998.7230

Cited by 26 publications

(18 citation statements)

References 48 publications

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“…It has been argued, for example, that increased exposure to sunshine during the first trimester of gestation may inhibit maternal melatonin production and stimulate the release of growth hormone (GH). Although high levels of melatonin are typically associated with high levels of GH (Laartz, Losee-Olson, Ge, & Turek, 1994;Zeman, Buyse, Lamosová, Herichová, & Decuypere, 1999), there is some evidence in both deer (Webster, Corson, Littlejohn, Stuart, & Suttie, 1998) and humans (Bellastella et al, 1994) for an inverse relation between melatonin and GH production. From this perspective, greater exposure to light during the first trimester of gestation may increase GH levels by inhibiting melatonin production.…”

Section: Discussionmentioning

confidence: 97%

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Maternal exposure to first‐trimester sunshine is associated with increased birth weight in human infants

Tustin

Gross

Hayne

2004

Developmental Psychobiology

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Two alternative hypotheses have been generated to account for seasonal variation in the birth weight of human infants born in industrialized countries. First, it has been hypothesized that low ambient temperature during the second trimester of gestation decreases birth weight. Second, it has been hypothesized that exposure to bright sunshine during the first trimester increases birth weight. We tested these two hypotheses to determine which, if either, accounted for seasonal variation in birth weight of full-term infants. Birth weight data, collected over a 5-year period, were analyzed as a function of peak and trough sunshine and ambient temperature. Although there was no effect of ambient temperature during any trimester on birth weight, infants whose mothers were exposed to peak sunshine during their first trimester were born significantly heavier than infants whose mothers experienced trough levels of sunshine during the same trimester. Furthermore, infants whose mothers were exposed to trough levels of sunshine during their second and third trimesters were born significantly heavier than infants whose mothers were exposed to peak levels of sunshine during the same trimesters. We hypothesize that high levels of sunshine during early gestation may increase the level of insulin-like growth factor (IGF)-1, facilitating prenatal growth.

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Section: Discussionmentioning

confidence: 97%

“…Relevant to the present study, there also is evidence that IGF-1 levels vary with exposure to light. For example, Webster et al (1998) showed that male red deer exposed to a simulated short-day cycle exhibited an earlier cessation of growth that was accompanied by a decrease in both IGF-1 and GH levels relative to animals that were Figure 2.…”

Section: Discussionmentioning

confidence: 97%

Maternal exposure to first‐trimester sunshine is associated with increased birth weight in human infants

Tustin

Gross

Hayne

2004

Developmental Psychobiology

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“…However, the association of the decline in GH across the fast in both sexes with reduced rates of protein loss was puzzling. Growth hormone increases in response to fasting in most species and is important in the conservation of protein during fasting (Eigenmann et al, 1985;Ho et al, 1988;Webster et al, 1999). Thus, despite evidence that increased suppression of GH levels negatively influences rates of protein catabolism in individuals, suppression of mean GH levels across the fast was associated with reduced rates of protein loss as measured from urea turnover.…”

Section: Discussionmentioning

confidence: 99%

Sex differences in fuel use and metabolism during development in fasting juvenile northern elephant seals

Kelso

Champagne

Tift

et al. 2012

Journal of Experimental Biology

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SUMMARYMany polygynous, capital breeders exhibit sexual dimorphism with respect to body size and composition. Sexual dimorphism is often facilitated by sex differences in foraging behavior, growth rates and patterns of nutrient deposition during development. In species that undergo extended fasts during development, metabolic strategies for fuel use have the potential to influence future reproductive success by directly impacting somatic growth and acquisition of traits required for successful breeding. We investigated sexual dimorphism associated with metabolic strategies for fasting in developing northern elephant seals. Thirty-one juvenile seals of both sexes were sampled over extended fasts during annual autumn haul-outs. Field metabolic rate (FMR) and the contribution of protein catabolism to energy expenditure were estimated from changes in mass and body composition over 23±5days of fasting (mean ± s.d.). Protein catabolism was assessed directly in a subset of animals based on urea flux at the beginning and end of the fast. Regulatory hormones and blood metabolites measured included growth hormone, cortisol, thyroxine, triiodothyronine, insulin, glucagon, testosterone, estradiol, glucose, urea and -hydroxybutyrate. Males exhibited higher rates of energy expenditure during the fast but spared body protein stores more effectively than females. Rates of protein catabolism and energy expenditure were significantly impacted by hormone levels, which varied between the sexes. These data suggest that sex differences in fuel metabolism and energy expenditure during fasting arise early in juvenile development and may play an important role in the development of adult traits associated with reproductive success.

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“…Similarly, thyroid hormone levels also are decreased during denning, and testing with thyrotropin-releasing hormone indicates that this reflects changes in hypothalamic function (2). Webster et al (43) have reported that photoperiod contributes to seasonal regulation of GH secretion and IGF-I levels in reindeer. It is interesting to speculate that seasonal changes in day length may also contribute to alterations in GH secretion in black bears in autumn and early denning, when IGF-I levels decline, and in later denning, when IGF-I levels increase.…”

Section: Discussionmentioning

confidence: 99%

Seasonal regulation of the growth hormone-insulin-like growth factor-I axis in the American black bear (Ursus americanus)

Blumenthal

Morgan-Boyd

Nelson

et al. 2011

American Journal of Physiology-Endocrinology and Metabolism

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The American black bear maintains lean body mass for months without food during winter denning. We asked whether changes in the growth hormone/insulin-like growth factor-I (GH-IGF-I) axis may contribute to this remarkable adaptation to starvation. Serum IGF-I levels were measured by radioimmunoassay, and IGF-binding proteins (IGFBPs) were analyzed by ligand blotting. Initial studies in bears living in the wild showed that IGF-I levels are highest in summer and lowest in early winter denning. Detailed studies in captive bears showed that IGF-I levels decline in autumn when bears are hyperphagic, continue to decline in early denning, and later rise above predenning levels despite continued starvation in the den. IGFBP-2 increased and IGFBP-3 decreased in early denning, and these changes were also reversed in later denning. Treatment with GH (0.1 mg·kg−1·day−1 × 6 days) during early denning increased serum levels of IGF-I and IGFBP-3 and lowered levels of IGFBP-2, indicating that denning bears remain responsive to GH. GH treatment lowered blood urea nitrogen levels, reflecting effects on protein metabolism. GH also accelerated weight loss and markedly increased serum levels of free fatty acids and β-hydroxybutyrate, resulting in a ketoacidosis (bicarbonate decreased to 15 meq/l), which was reversed when GH was withdrawn. These results demonstrate seasonal regulation of GH/IGF-I axis activity in black bears. Diminished GH activity may promote fat storage in autumn in preparation for denning and prevent excessive mobilization and premature exhaustion of fat stores in early denning, whereas restoration of GH/IGF activity in later denning may prepare the bear for normal activity outside the den.

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Effects of Photoperiod on the Cessation of Growth during Autumn in Male Red Deer and Growth Hormone and Insulin-like Growth Factor-I Secretion

Cited by 26 publications

References 48 publications

Maternal exposure to first‐trimester sunshine is associated with increased birth weight in human infants

Maternal exposure to first‐trimester sunshine is associated with increased birth weight in human infants

Sex differences in fuel use and metabolism during development in fasting juvenile northern elephant seals

Seasonal regulation of the growth hormone-insulin-like growth factor-I axis in the American black bear (Ursus americanus)

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